"Also, how so?"
As in, why not the same?
If so, your option A defined a "routed" port, i.e. much like a router would use. Such a port should have an IP directly assigned to it. (You later ask, wouldn't the server have an IP. Yes it would, but it needs a gateway IP to reach other hosts not on the same network. This is what the IP on such a port would provide. I.e. without an IP on such a port, it's, more-or-less, useless.)
Option B creates a VLAN port, which allows multiple hosts to use and be on the same L2 broadcast domain. (Again, for hosts on the VLAN, they will need a gateway IP to get on/off that VLAN. On a L3 switch, often a SVI provides that, but a router or L3 switch "routed" port [option A] might provide a GW IP too. [In theory, on the same L3 switch, you could connect your server, and other hosts, to access ports, same VLAN, and then connect an access port, same VLAN, to a "routed" port, with IP, on the same L3 switch. Using an SVI, instead, not only saves using two physical ports, a SVI should be able to handle the aggregate bandwidth of all its ports assigned to its VLAN.])
